146 research outputs found
Inclusive probability to record an electron in elastic electromagnetic scattering by a spin one-half hadron wave packet
The inclusive probability to record an electron in elastic electromagnetic
scattering of an electron by a spin one-half hadron is obtained, the initial
quantum states of the electron and the hadron being described by the density
matrices of a general form. Contrary to the Rosenbluth formula for the
differential cross-section for this process, the first nontrivial contribution
to the inclusive probability turns out to be of order and not
. This contribution describes the interference between the trivial
contribution to the -matrix and the leading contribution to its connected
part. The explicit expression for this interference terms is derived. It is
shown that the same interference term arises when the electron is scattered by
the classical electromagnetic field produced by the hadron electromagnetic
current averaged with respect to the free evolving density matrix of the
hadron, even in the case of a single hadron. The interference term describes
coherent scattering of the electron by the hadron wave packet and is immune to
the quantum recoil experienced by a hadron due to scattering. The effective
electron mass operator is found on the mass-shell.Comment: 14 pp., 2 fig
Three-body breakup within the fully discretized Faddeev equations
A novel approach is developed to find the three-body breakup amplitudes and
cross sections within the modified Faddeev equation framework. The method is
based on the lattice-like discretization of the three-body continuum with a
three-body stationary wave-packet basis in momentum space. The approach makes
it possible to simplify drastically all the three- and few-body breakup
calculations due to discrete wave-packet representations for the few-body
continuum and simultaneous lattice representation for all the scattering
operators entering the integral equation kernels. As a result, the few-body
breakup can be treated as a particular case of multi-channel scattering in
which part of the channels represents the true few-body continuum states. As an
illustration for the novel approach, an accurate calculations for the
three-body breakup process with non-local and local
interactions are calculated. The results obtained reproduce nicely the
benchmark calculation results using the traditional Faddeev scheme which
requires much more tedious and time-consuming calculations.Comment: 17 pages, 13 figure
Nature of -wave interaction and dibaryon production at nucleonic resonance thresholds
Phase shifts and inelasticity parameters for scattering in the
partial-wave channels -- and at energies from zero to about 1 GeV are described within a unified potential
model assuming the formation of isoscalar and isovector dibaryon resonances
near the threshold. Evidence for these near-threshold resonances
is actually found in the recent WASA experiments on single- and double-pion
production in collisions. There, the excitation of the Roper resonance
exhibits a structure in the energy dependence of the total cross
section, which corresponds to the formation of dibaryon states with
and at the threshold. These two
-wave dibaryon resonances may provide a new insight into the nature of the
strong interaction at low and intermediate energies.Comment: 10 pages, 8 figure
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